1. Field of the Invention
The present invention relates to a heat exchanger constructed by a plurality of plates forming inside fluid passages through which an inside fluid flows, and applicable to a refrigerant evaporator for a vehicle air conditioning apparatus.
2. Description of Related Art
Conventionally, as shown in FIGS. 28, 29A and 29B, a refrigerant evaporator for a vehicle air conditioning apparatus is constructed by laminating alternately a plurality of oval flat tubes and corrugated fins having louvers to increase an air side heat conductive area. Each oval flat tube is formed by connecting a pair of plates facing each other at the outer peripheries thereof. An assembling process of this heat exchanger becomes complicated because the corrugated fin is disposed between the adjacent oval flat tubes. That is, as the conventional heat exchanger needs a corrugated fin, it is. difficult to reduce the manufacturing cost and the size of the heat exchanger.
In the air conditioning unit, the evaporator is generally formed into rectangular parallelopiped shape, as shown in FIG. 28. This is because it is difficult to form the outer shape of the corrugated fin into any shapes other than the rectangular parallelopiped shape for the reason that the corrugated fin is formed by press-forming a thin coil-like material into waved shape as shown in FIGS. 29A and 29B. As a result, the evaporator must be formed into the rectangular parallelopiped shape along the outer shape of the corrugated fin.
An object of the present invention is to provide a heat exchanger, which is constructed by only a heat conductive plate forming an inside fluid passage while dispensing with fin-members such as a corrugated fin and attaining a sufficient heat transmitting performance.
According to the present invention, a pair of heat conductive plates forming a heat-exchanging core portion has a plurality of projection ribs. The projection ribs protrude outwardly from the pair of heat conductive plates for forming inside fluid passages therein. An outside fluid flows outside the heat conductive plate perpendicularly to a flow direction of an inside fluid, and is prevented from flowing straightly by the projection ribs.
Thus, the outside fluid makes a turbulent flow, thereby further improving the outside fluid side heat transmitting efficiency. As a result, a desired heat-exchanging performance can be attained without providing a fin member at the outside fluid side. That is, the heat exchanger can be constructed by only the heat conductive plate having the projection ribs forming the inside fluid passages. Thereby the total cost for manufacturing the heat exchanger and the size of the same are reduced. Further, because the rigidity of the entire heat exchanger is increased, the heat conductive plate can be made thin, and the total cost and size of the heat exchanger is further reduced.
Further, the heat exchanger is constructed by only the heat conductive plate, the heat-exchanging core portion may be formed into a rectangular parallelopiped shape having a triangular protrusion portion. The volume of the heat-exchanging core portion is increased by adding the protrusion portion, thus the heat-exchanging performance of the heat exchanger is improved. When the heat exchanger is used as a refrigerant evaporator installed within an air conditioner casing, the protrusion portion can be formed by using an affordable space inside the air conditioner casing.